WHAT'S UP DOC? Stretch marks sign of childhood growth

Q: My son has never been overweight, but he has developed what looks like stretch marks on his lower back. Is this something I should be worried about? What can cause this?

A: Striae distensae (the medical name for "stretch marks") are a very common skin discoloration/scarring. They usually start off along lines of skin tension as red/purple linear streaks of atrophic skin, typically a fraction of an inch up to half an inch or more wide (and hence are called striae rubra). Over about six months to a year they become more of a white color (and hence are called striae alba), then eventually fade (to a varying extent) over many months to years. They are most commonly located on the abdomen, lower back, hips, arms, breasts, upper arms and/or thighs.

The reason striae distensae develop is not completely understood. They may be causes by many factors, including mechanical stress on the skin (this is the reason they may develop when there is a rapid stretching of the skin, such as during pregnancy or a rapid growth spurt in an adolescent, and is the reason they are often called stretch marks), hormonal changes (another reason they may develop during pregnancy or adolescence, and also why they may occur in certain diseases such as Cushing’s Syndrome, which is a condition where the steroid hormone level is abnormally high) and other diseases that alter/affect the skin.

Striae distensae are usually benign, although if they are due to an underlying condition then the medical ramifications of that condition must be assessed and treated as indicated. However, the cosmetic appearance of striae distensae may cause concern for the patient.

Striae distensae are very common, affecting most pregnant women (to varying extents), many people who have their body mass index change significantly (especially if the change is large and rapid), and up to 70 percent of females and 40 percent of males during adolescence.

The diagnosis of striae distensae is made based on the characteristics of the lesions noted on physical examination. Although skin biopsy can verify the diagnosis, this is not usually needed.

Since these skin lesions usually fade over time, unless they cause concern for the patient due to their cosmetic appearance, no treatment is usually required. If treatment is indicated (typically due to the preferences of the patient) there are multiple options, including laser therapy (with many variations of the type of laser and the specific treatment protocol used), superficial dermabrasion, phototherapy, over the counter topical agents/medications (although there is limited data on the efficacy of many of these), chemical peels, certain prescription topical medications (for example retinoids), as well as other therapies. The efficacy of these different treatments has not been tested in any head to head controlled clinical trials that I was able to find. Therefore, if the patient has concern over the cosmetic appearance of their striae distensae they should discuss the possible treatment options with their dermatologist.

Since striae distensae are so common from pregnancy there has been consideration of using certain topical creams/treatments to prevent them. However, there is very limited evidence regarding the effectiveness of this approach. This may be a good topic to discuss with your obstetrician to see what their recommendation may be.

If you think your adolescent child has developed "stretch marks," you should have them see their pediatrician to have the diagnosis confirmed. Typically, reassurance and education about the typical course of these skin lesions is all that is needed. Your pediatrician will also do a thorough history to be sure there is no concern for a medical condition (or even steroid abuse) as the cause of the striae distensae.